Methods for manufacturing cementitious reinforced panels

ABSTRACT

Reinforced facings, including reinforcing webs entrained in hydraulic cement via a slurry bath, adhere to a nailable lightweight aggregate cementitious core to form a panel web. The reinforced web is formed on abutting conveyed carrier sheets, and the web is transversely cut, between the sheets, while moving or when stopped, in response to sensing of the sheets. The cut panels, on respective sheets are stacked for curing without damaging the panel edges and in a manner to minimize panel flex. Slurry bath, facing applicators, and cutter and stacking apparatus are included.

This invention relates to methods and apparatus for manufacturingconstruction panels and more particularly, reinforced cementitiouspanels of the type generally described in U.S. Pat. No. 3,284,980. Thesepanels typically include a cementitious aggregate core layer faced withreinforcing mesh adhered thereto with hydraulic cement. In many cases,the core is so substantially drier than the cement on the mesh, that itmay in fact be crumbly in texture.

Reinforced cementitious panels of the type noted are extremely useful inthe construction industry, yet heretofore no entirely suitable methodsand apparatus for economically manufacturing commercially useful panelshave been known. While the patent noted describes one way to manufacturethe panels by the use of individual forms, the increased demands formany panels can only be economically satisfied by production methodshaving a greater output capacity.

Moreover, prior known methods of panel manufacture have been attended byproblems in the adherence of the facings to the core layer and in thecutting, and stacking procedures. For example, separation of the facingfrom the core is highly undesirable since it destroys the integrity ofthe panel, and its desired strength characteristics. Too littlehydraulic cement on the core side of the reinforcing mesh is onepotential cause for such separation, particularly when the difficulty ofbonding the facing to any aggregate crumbly core is considered.

Another potential cause has to do with movement of the panel prior tothe time it is cured. Flexing of the panel can cause the layers to movewith respect to each other, and thus to separate. Such flexing can occurin the stacking operation where the panels are stacked for curing.

Another exemplary difficulty is encountered in maintaining clean paneledges. Wide blade guillotine type cutting techniques have not been foundsuitable as they tend to produce ragged or inclined edges. Also, theedges can be disturbed by handling or movement of the panel prior tocuring.

Accordingly, the present invention contemplates novel methods andapparatus for economically manufacturing and producing useful, integralreinforced cementitious panels having a lightweight aggregate core andreinforced cementitious facings. In a preferred embodiment of theinvention, such a panel is manufactured by the steps of running acontinuous web of fiberglass reinforcing mesh through a cementitiousslurry bath to fill voids in, and accumulate on, both sides of, themesh; doctoring excess slurry therefrom; laying the wet mesh on aplurality of thin moving abutted carrier sheets; depositing alightweight, low-moisture content aggregate core material on the mesh;compacting the aggregate core material; running a second continuous webof fiberglass mesh through a cementitious slurry bath; doctoring excessslurry therefrom; laying the second wet mesh on the compacted aggregatecore material to form a panel web; cutting the panel web transverselythereacross and between the carrier sheets to form separate panels; andthereafter stacking the cut panels on one another for curing in a mannerto minimize flexing the panel and disturbance of its edges.

An associated aspect of the invention includes dragging each of thefiberglass webs as they are placed respectively on the carrier sheetsand on the core material in order to drive slurry through the mesh, theslurry operatively bonding the meshes to the relatively dry and crumblyor no slump lightweight core.

A further aspect of the invention resides in forming a continuousreinforced cementitious panel on a plurality of carrier sheets, and intransversely cutting the continuous panel web into preselected panelsizes corresponding to the length of the carrier sheets. In a preferredembodiment, the carrier sheets abut end to end on a belt conveyor. Eachcarrier sheet is sensed to actuate a cutter drive operable to draw aknife across the panel web, transversely thereto, in order to cutindividual panels from the panel web between the carrier sheets. Moreparticularly, each carrier sheet is provided with a metallic rivet nearthe front edge thereof. A metallic proximity sensing apparatus under theconveyor belt senses the rivet and actuates a cutter across the panelweb between the abutting carrier sheets. The cutter is mounted on acarriage driven swing arm, and moves with a component of motion in themachine direction, while at the same time cutting transversely acrossthe moving panel web, all to permit cutting during continuous movementof the panel web. The cutoff panel is accelerated away from thefollowing panel web by an overspeed belt to a panel stacking apparatusfor curing and storage. In an alternate method, a cutter is mounteddirectly to the carriage and cuts panels at a time when the carriersheets are stopped, having leading and trailing edges indexed to thecutter position via the sensing apparatus.

After cutting, and in another aspect of the invention, the panels areintroduced to a stacker table having drop plates which slide to thesides and drop the carrier sheet and cementitious panel thereon aminimal distance onto a stack of previous panels. The stack is supportedby an indexable support which drops a distance equal to a panelthickness upon each stacker operation. The cementitious panels are curedin these stacks and are thereafter ready for storage or use.

Where the drop plates withdraw from beneath the panels, the panels, andcarrier sheets flex and sag in the middle and this sagging can causeseparation of the panel layers. In order to minimize panel flex duringdropping, and to preserve edge integrity, the drop plates are preferablytapered so that upon their withdrawal, support is first removed from thepanel corners, then from the panel center. This minimizes overall flexand reduces or eliminates layer separation. Thus the drop platestructure interacts with the minimal drop distance provided by theindexable stack to significantly reduce panel flex and layer separation.

Accordingly, the invention provides apparatus and methods whereby acementitious slurry wetted reinforcing mesh is operably adhered to bothsides of a relatively lightweight, low moisture, cementitious aggregatecore and the formed web is thereafter cut to individual panels which arestacked for curing. The invention provides an economical and high outputcapacity manufacturing process, all without disturbing the panel's edgeor layer bond integrity.

These and other advantages will become readily apparent from thefollowing detailed description of a preferred embodiment of theinvention and from the drawings in which:

FIG. 1 is an exploded view of a panel and carrier sheet according to theinvention;

FIG. 2 is a flow chart illustrating methods according to the invention;

FIGS. 3A and 3B are elevational diagrammatic views of panelmanufacturing apparatus according to the invention, FIG. 3B differingsomewhat in scale from FIG. 3A for clarity;

FIGS. 4-7 are top view of a preferred panel web cutter according to theinvention;

FIG. 8 is a cross sectional view of the cutter taken along lines 8--8 ofFIG. 6;

FIG. 9 is a top view of an alternate panel web cutter according to theinvention;

FIG. 9A is an end view of the alternate panel web cutter taken alonglines 9A--9A of FIG. 9;

FIG. 10 is a plan view of a stacking apparatus according to theinvention, taken along lines 10--10 of FIG. 3B;

FIG. 11 is an end view of the stacking apparatus taken along lines11--11 of FIG. 3B; and

FIG. 12 is a control flowchart illustrating operation of the stackerapparatus.

Panel Forming

Turning now to the drawings, FIG. 1 is an illustrative exploded view ofa preferred panel manufactured by the methods and apparatus of thepresent invention. The details of the panel are best described in detailin U.S. Pat. No. 3,284,980 to P. E. Dinkel entitled "Hydraulic CementPanel with Low Density Core and Fiber Reinforced High Density SurfaceLayers," which patent is expressly incorporated herein by reference. Asshown in FIG. 1, however, the panel 10 to which this disclosure isdirected generally constitutes a reinforced nailable cementitiousstructural panel comprising a core layer 11, a facing including areinforcing element 12 on one major side of the core layer 11 and areinforced facing 13 including a reinforcing element on another majorside of the core 11.

The core 11 constitutes a lightweight concrete made up of a lightweightaggregate and hydraulic cement, the relationship of aggregate to cementbeing such that the core layer is relatively dry and crumbly, or with ano slump characteristic, as compared to the reinforced facing layers, aswill be described. For example, the core layer contains a mix of aboutthree or four parts of aggregate by volume to each part of hydrauliccement, thus providing a nailable layer. Further details of the core aredisclosed in the cited U.S. Pat. No. 3,284,980.

The reinforced facings preferably constitute fiber mesh-like perviouswebs 12 and 13, each entrained, according to the invention, in hydrauliccement. As will be described, the hydraulic cement is applied to themesh reinforcing elements 12 and 13 such that the hydraulic cementsubstantially fills the interstices in the fiber layer and covers theouter faces of the layer. The further details of the reinforcingelements are also found in the cited U.S. Pat. No. 3,284,980. Each ofthe reinforcing elements are relatively thin i.e. on the order of, forexample, 0.125 inch thick, and the entire cementitious panel 10including core layer 11 and facings preferably constitute a structuralpanel from, for example, about one-quarter inch thickness to and beyond,for example, two inches in thickness, depending upon desired end use. Ofcourse, thinner reinforcing elements are utilized for thinner panels, asnecessary.

While the cited U.S. patent demonstrates one method of manufacturingpanels, the production of a substantial number of panels requires amanufacturing process having a high capacity output while at the sametime producing a useful, integral panel having layers which arethoroughly bonded to each other and having relatively straight nonraggedand undisturbed edges. According to the cited U.S. patent, the panelsare manufactured by the application of various layers to each other indistinct separate molds, and subsequent curing.

Prior to curing, flexing of the panel has the tendency to cause thevarious layers of the panel to move with respect to each other and toseparate, thereby destroying the integrity of the panel and reducing thedesired strength characteristics of the panel. Thus, it is highlydesirable in the manufacture of separate panels to avoid any flexing ofthe panel, thereby to minimize layer separation and to enhance theintegrity of the panel. In addition, it is highly desirable to provide apanel with smooth parallel edges, both for aesthetic reasons and forresistance of the panel to any elements to which it will be exposed.

It has been known to manufacture cured concrete in elongated cured form,and thereafter to cut it into separate panels. The present invention, aswill now be described, produces separate cut and stacked reinforcedcementitious panels all prior to curing and with minimal panel flexduring the forming operation and with uniform nonragged edges, all toprovide an integral useful panel in a high output capacity manufacturingprocess. To these ends, and as shown in FIG. 1, panel carrier sheets 20are provided for each to-be-formed panel 10. The carrier sheets 20,according to the invention, are approximately one-eighth inch thick andare preferably made from a plastic material such as polyethylene. Eachcarrier sheet 20 includes, proximate an end 21 thereof, a metallicelement, such as a rivet 22, for sheet sensing purposes, as will behereinafter described. Each carrier sheet is normally flat, having noraised ends or sides, and is somewhat flexible. As heretofore stated,the bonding of the reinforcing elements 12 and 13 to the core layer 11of the panel is extremely important to the integrity of the panel and toits strength characteristics. One aspect of the invention accordinglyprovides for the bonding of a reinforcing element to a crumbly,relatively dry, cementitious aggregate core layer simply by virtue ofthe entraining of the reinforcing element in a hydraulic cement wherebythe hydraulic cement serves to bond the reinforcing element to the core.In order to provide for maximum bonding of the reinforcing element tothe core, the invention contemplates a method for entraining thereinforcing elements within the hydraulic cement such that the cementtends to fill the voids of the mesh-like reinforcing element, and toaccumulate on the outer surfaces of the element, thereby to bond theelement to the core and to form a desired outer facing surface. At leastthe first reinforcing element tends to float in the slurry during panelformation.

The flow chart of FIG. 2 depicts the method steps by which the panel isformed according to the invention. FIGS. 3A and 3B diagrammaticallyillustrate the features of a panel manufacturing process, whichcorrespond to the steps illustrated in FIG. 2. Considering both FIG. 2and FIGS. 3A and 3B, it will be seen that a continuous web of amesh-like reinforcing element is fed through a first trough or slurrybath 30 wherein the slurry material 31 therein constitutes hydrauliccement mixture as described in U.S. Pat. No. 3,284,980. As shown in FIG.3A, the elongated reinforcing element 12 is drawn through the slurrybath 30 by virtue of a roller 32 such that the hydraulic cement 31 isapplied to both sides of the elongated reinforcing web 12. Thereafter,the reinforcing web is pulled from the bath 30 around roller 33 and anyexcessive slurry is doctored from the web 12 by virtue of an adjustabledoctoring blade or metering apparatus 34, which can be adjusted tocontrol the amount of slurry actually applied to the web 12.

From the metering apparatus 34, the web 12 then travels downwardly to apoint where it is layed onto a plurality of carrier sheets 20. Each ofthe carrier sheets is supported and conveyed by a conveyor belt 25 withthe sheets in abutting relationship so that a forward end of eachcarrier sheet preferably contacts the trailing end of a precedingcarrier sheet. While it may be possible to lay the slurried web 12 ontocarrier sheets which are spaced apart, it is preferable to lay thecarrier sheets end to end in abutting relationship as described in orderto maintain uniformity of the panel face. The carrier sheets can beplaced on the conveyor belt upstream of the slurry bath 30 by anyappropriate means, which do not constitute part of this invention.

Continuing now with the description of the method by which the panel 10is formed, the slurried web 12 is layed down on the carrier sheets byvirtue of a drag bar 35, which is positioned above the web and whichdrags against its upper surface, thereby serving to urge hydrauliccement on the upper surface of the web into the interstices of the weband through the web. It should be appreciated, however, that the dragbar does not remove or scrape from the mesh all of the hydraulic cement,but rather leaves a quantity of cement on the upper surface of the web.

Proceeding from the drag bar 35, the conveyed carrier sheets and webmove beneath the core mix feeder 40. The core mix feeder 40 constitutesa hopper 41 terminating over a belt conveyor 42, which transfers theaggregate cementitious core mix through an adjustable metering gate 43for controlling the amount of mix layed onto the slurried mesh 12.

The core mix 44 is thus fed from the hopper 41 onto the belt 42, andthereafter through the gate 43 onto the slurried mesh web 12 as shown inFIG. 3A.

At least the upper layer of the core mix between the core mix feeder 40and the rough screed 45 is not uniform. The rough screed 45 counterrotates in the direction of arrow 45A to smooth out the upper surface ofthe core layer 11. Thereafter, a finish screed 46, which counter rotatesin a direction of arrow 46A, serves to reduce the thickness of the corelayer 11, and to further smooth the upper surface thereof. Thereafter,the conveyor belt moves the abutting carrier sheets 20, the slurriedmesh 12 and the core layer 11 into a compaction station formed bycompaction roll 47, which serves to compact the core 11 against theslurried mesh 12. This enhances the bond of the slurried mesh to therelatively crumbly core.

Thereafter, an elongated reinforcing mesh-like element in the form of acontinuous web 13, is fed through a second slurry bath or trough 50containing a slurry 51, also of the hydraulic cement-mixture previouslydescribed. The web 13 is drawn through the bath 50 by virtue of theroller 52, and thereafter past roller 53 and a second adjustable doctorblade or metering apparatus 54 for controlling the amount of slurryapplied to the web 13. Both metering apparatus 34 and 54, and the firstand second slurry baths can be of any suitable form constituting, withtheir respective backup rollers and adjustable gate, a slurry to meshapplicator for passage of the mesh with an appropriate amount of slurrythereon. The slurry metering can be accomplished in any suitablefashion.

From the metering apparatus 54, the web 13 is conveyed onto the uppersurface of the compacted core layer 11 by virtue of a second drag bar 55at which point the mesh is layed down on top of the core layer. The dragbar 55 is operable to urge the hydraulic cement on the mesh element 13into the interstices thereof and through the mesh, so that a sufficientamount of hydraulic cement resides on lower surface of the mesh element13 and thereby contacts the surface of the core layer 11 for bonding theelement 13 thereto. Subsequent stacking for curing serves to enhance thebond.

From the drag bar, the continuous panel web, including a slurried lowermesh element 12, a core layer 11 and a slurried upper mesh element 13,is conveyed into a cutter station as depicted in FIG. 3B. Thisillustration, for clarity, shows the formed panel web in lesser detailthan in FIG. 3A.

The cutter station includes a cutter 60 for moving transversely acrossthe formed panel web and cutting the web between adjacent and abuttingcarrier sheets. The details of the cutter will be hereinafter described.

From the cutter 60, the now individual panel 10, and its respectivecarrier sheet 20, is conveyed onto an overspeed conveyor 90, operatingat a speed in excess of that of conveyor 25, to separate a cut panel andcarrier sheet from the integral continuous formed panel web upstream ofthe cutter 60. Once the now cut panel and associated carrier sheet ismoved onto the overspeed conveyor 90, it is sensed, as will bedescribed, and is pushed from the overspeed conveyor, via pusher 96,onto the stacking apparatus 110. Stacker 110 serves to form a stack 111of assemblies, each of which comprise a carrier sheet with a reinforcedpanel 10 thereon. When a full stack 111 is formed, the stack is conveyedaway from the stacking apparatus 110 for further curing and storing.Once cured, the panels are ready for use in many construction andremodeling applications. As will be appreciated, various panel facetexturizing means could be provided to texturize the hydraulic cement onthe panel face to any desired design.

Returning now to a more detailed description of the cutting apparatus,FIGS. 4 through 7 depict a preferred cutting apparatus, which isoperable to cut the continuous panel web transversely and between thecarrier sheets during movement of the panel web in the machinedirection, which is indicated by the arrows MD in the various drawings.The combination of the transverse cutting apparatus and its operation,when taken together with forming the continuous panel web on abuttingcarrier sheets, constitutes a unique means by which separate uncuredpanels can be cut to provide uniform panel edges without distortion andraggedness of that edge. Furthermore, it should be noted that theability to cut separate panels from the continuously formed panel web,all while the web continues to move significantly increases the outputcapacity of the manufacturing process.

The Panel Cutter

Turning now to the details of the cutter operation, and first to FIG. 8,it will be noted that the rivet 22 has been located in the forward orleading edge 21 of a respective carrier sheet as shown in FIG. 8. Thecutter, as will be described, is actuated into a cutting traverse of thepanel web upon an appropriate sensing of the rivet 22. This sensing canbe accomplished, for example, by way of a metallic proximity switch 23,such as, for example, a proximity switch manufactured by theAllen-Bradley Company under its Bulletin No. 870. Upon sensing theproximity of the rivet 22 at the position as shown in FIG. 8, theproximity switch signals a cutter drive motor 61 to operate the cutterand thereby cut the panel between the abutting carrier sheets.

For the purposes of description of the cutter operation in FIGS. 4through 7, three different panels or panel webs 1, 2, and 3, as the casemay be, will be considered. As shown in FIG. 4, for example, panel webportion 1 is a portion of a continuously formed panel web, no cutshaving yet been made. In FIG. 5, a cut has partially been made toseparate the to-be-formed individual panel 1 and its associated carriersheet from the leading edge of the following continuous panel webdesignated by the numeral 2. In FIG. 6, the cut is substantiallycompleted so that the panel 1 now constitutes a separate cut panelsimilar to the cementitious panel 10 of FIG. 1, while the continuouspanel web following is designated by the numeral 2. The web 2 has aleading edge defining by leading edge 21 of a carrier sheet and separatepanel 1 has a trailing edge, coextensive with the trailing edge 24 ofthe carrier sheet on which the panel 1 is carried.

In FIG. 7 the continuous panel web, designated by the numeral 2, has nowmoved forwardly sufficiently in the machine direction so that afollowing carrier sheet, beneath the web portion including to-be-formedpanel 3, is now moved into the cutter station. Hereafter, the cutterapparatus will be actuated in a direction opposite to its first cuttingtraverse to cut panel 2 from the following panel web 3, between therespective carrier sheets as depicted in FIG. 7.

Turning now to the details of the cutter apparatus, the cutter 60comprises a cutter drive motor 61 mounted to drive a carriage 62transversely across the panel web on a track 63. Track 63 can be framemounted (not shown) across the web in any suitable fashion.

The motor 61 is suitably mounted on the track 63, or the supportingframe thereof, and is connected to the translatable carriage 62 via acable 64, having ends connected to opposite sides of the carriage 62 asshown in the drawings. The motor 61 is reversible so that it alternatelydrives cable 64 in one direction, and then in the other, in response toactuation by an appropriate motor control, which is activated by theactuation of proximity switch 23 upon sensing the rivet 22.

The preferred cutter also includes a swing arm 65 on which is mounted acutter blade 66. Swing arm 65 is pivoted at 67 to the carriage 62 and isurged by spring 68 into the positions shown in FIGS. 4 and 7. It shouldalso be noted that the cutter blade 66, which is approximately twoinches wide and double edged, is pivoted at 69 to the swing arm 65. Whenthe carriage is in its extreme positions, as shown in FIG. 4 and FIG. 7,the spring 68 is operable to rotate the swing arm 65 about the pivot 67in a clockwise direction and to thereby urge the pivoted cutter blade 66against the respective stops 70 and 71, thereby to position the pivotedcutter blade 66 at a 90 degree angle with respect to the machinedirection and the longitudinal axis of the panel web. Thus the cutterblade 66 is positioned parallel to the leading and trailing edges 21 and24 of the carrier sheet 20, and perpendicular to the elongated edges ofthe panel. Thus when the rivet 22 is sensed at the cutter station, themotor 61 is actuated to drive the carriage 62 across the web, wherebythe cutter blade 66 enters the panel web between the leading andtrailing edges of adjacent and abutting carrier sheets, and cuts acrossthe panel web to separate, for example, panel 1 from panel web portion2, as shown in FIGS. 4, 5 and 6. Since the panels are constantly movingin the machine direction during the cutting operation, it will be seenfrom FIGS. 4 through 6 that the pivot axis of the cutter blade actuallytraverses a diagonal path 75, as shown in the figures, while the actualcut is made between the carrier sheets on a line perpendicular to theedges of the panel web, the cut line being shown in dotted form atnumeral 76.

Once the panel 1 has been cut from the panel web portion 2, the carriage62 moves to the extreme position as shown in FIG. 7, where it residesuntil a succeeding rivet 22 is sensed in the next carrier sheet cominginto the cutting station. At this point in time, the trailing end of theto-be-formed panel 2 has moved to the cutting area and the leading edge21 of the carrier sheet under the continuous panel web portion 3immediately follows.

When the rivet 22 is sensed, the motor control is signaled via switch 23to energize the motor to drive the carriage 62 back across the panel webin an opposite direction, from its traversing movement in FIGS. 4through 6, to cut along the intended cut line 77 and thereby separatethe to-be-formed separate panel 2 from the continuous panel web portion3. The cut, of course, is made between the trailing edge 24 of thecarrier sheet under panel 2 and the leading edge of the carrier sheetunder the panel web portion 3. As shown in FIG. 7, since the panel andpanel web are moving in the machine direction during operation of thecutter 60, the pivot point 69 actually traverses a diagonal lineindicated at 78 in FIG. 7, yet a straight cut is made across the panelweb by virtue of the cutter blade 66 being guided between the trailingedge 24 of the carrier sheet for the panel 2 and the leading edge 21 ofthe carrier sheet under the panel web portion 3.

Of course, it will be appreciated that the spacing between the proximityswitch 23 and the actual cutter position, in its stopped location, isimportant. In this regard, it should be noted that the proximity switch23, and the motor control are set up by any suitable fashion, well knownin the art, to control the motor 61 to drive the cutter blade 66 intothe panel web at that point in time, in relation to sensing of the rivet22, at which the cutter blade 66 is aligned with the leading andtrailing edges of abutting carrier sheets. Thus the cutter blade entersthe panel web and is thereafter guided by virtue of abutment with theedges of the carrier sheets. The particular motor control forms noportion of this present invention and any motor control, which incombination with the proximity switch is suitable to drive the cutterblade into the panel web at the appropriate position, can be used.

As will be appreciated, as the cutter is driven across the panel web,the continued motion of the web tends to pull the swing arm 65 about thepivot 67 and away from the carriage 62, but as soon as the cutter bladeclears the panel web, the spring 68 is operable to draw the swing arm 65back into its initial starting position for making its next cuttingtraverse across the panel web, and to urge the cutter blade against thestop 71 to position it for the next cut.

Turning now to FIGS. 9 and 9A there is shown an alternate embodiment ofa cutting apparatus 60A wherein parts which are similar to the preferredcutting apparatus will be designated by identical numerals together withthe suffix "A". In FIG. 9, a motor 61A is controlled by a motor controlto drive a carriage 62A across a track 63A transversely to a panel web.FIG. 9 shows the carriage 62A in position on one side of the web insolid lines, and in phantom on the other side of the web subsequent tohaving made a cut along an intended cut line 81, between the trailingand leading edges of abutting carrier sheets beneath the continuouspanel web. This embodiment differs from the preferred embodiment in thatthe cutter blade 66A is positively mounted to the carriage 62A and doesnot pivot away therefrom. Accordingly, it is also necessary in theoperation of this alternative embodiment to stop the conveyor 25 and theformed panel web at a point, in response to the sensing by proximityswitch 23A, so that the cutter blade 66A can be driven through the panelweb at the junction of two abutting stopped carrier sheets. Accordingly,a signal from the proximity switch 23A is also delivered to a conveyorcontrol in a suitable fashion for stopping the conveyor 25 at a timewhen the rivet 22 is sensed and the junction between abutting carriersis aligned with the cutter blade 66A. If necessary, the drivingapparatus (not shown) of the conveyor 25 can be braked in order toaccurately stop it so that the sensed carrier sheet has a leading edgein appropriate alignment with the cutter 66A. As contrasted to thepreferred embodiment, it is necessary to stop the panel web momentarilyin this embodiment, together with the panel component feeding features,as will be appreciated, but such stop is of very short duration.

Both the preferred and the alternate cutter embodiments are useful intraversing across the panel web, between abutting carrier sheets, to cutthe panel web thus separating individual panels therefrom which areequal in length to that of the carrier sheets thereunder. The cutters asdescribed form a uniform, nonragged panel edge.

From the cutting station, the cut panel is conveyed onto the overspeedconveyor 90, at which point the gap between the cut panel and thefollowing panel web is sensed by, for example, photo electric means 91of any suitable type. Upon sensing of the trailing edge of the cutpanel, indicated by the numeral 1 in FIG. 3B, the pusher 96 is activatedto engage the rear end of the panel 1 and push it onto the stackingapparatus 110.

The pusher 96 comprises a pusher dog 97 mounted to a suitable linkage(not shown) which is operable to traverse the pusher dog 97 in themachine direction, thereby pushing a panel 10 onto the stackingapparatus. Upon completion of the pushing motion of the dog 97, thelinkage of the pusher mechanism is operable to lift the pusher dog andreturn it in a direction opposite to the machine direction to theposition shown in the phantom lines at 98, where the dog is then inposition to lower, move forward, and engage the trailing edge of asucceeding panel.

Thus, it will be appreciated that the overspeed conveyor 90, operatingat a speed in excess of that of conveyor 25, is operable to separate thepanel 10 from the following continuous panel web. When the passage ofpanel 10 is sensed on the overspeed conveyor, the pusher dog 97 isoperated to lower and to travel in the machine direction to catch upwith panel 10 and push it onto the stacker.

The pusher dog 97 is movable in the machine direction to a positionshown at 99, which is approximately even with the leading edge 112 of adrop table 113 in the stacking apparatus 110. Since the panels may be ofvarying legnths, a stop 114 is provided, in association with thestacking apparatus, to limit the movement of the panel on the stackingapparatus in an appropriate position for stacking. Since the extrememovement of the pusher dog is to the position 99 at the leading edge 112of the drop table 113, it is shown that the leading edge 101 of thepanel 10 has not been yet moved to the stop 114; however, it should beappreciated that the momentum of the panel and the coefficient offriction between the plastic carrier sheet 20, and the upper surface ofthe drop table 113, is such that the assembly comprising the panel 10and the carrier sheet 20 will slide across the drop table to theposition of the adjustable stop 114, thereby properly positioning thepanel.

The Panel Stacker

The details of the stacking apparatus 110 will now be described. Asnoted above, the stacking apparatus comprises a drop table 113 which isoperable to drop panel assemblies, including a panel and a supportingcarrier sheet, onto a stack 111. After curing, the carrier sheets areseparated from the panels for re-use in the forming process.

The stack 111 is supported on a pallet 120, which in turn is supportedon a vertically movable pallet conveyor 125 operable, as will bedescribed, to convey a stack 111 away from the stacking apparatus 110.The drop table 113 comprises a plurality of drop plates 130 and 131, asbest seen in FIG. 10. The drop plates 130 and 131 are mounted torespective racks 132 and 133 and 134 and 135. These racks are driven byrespective pinions 136, which are rotated by appropriate drive means(not shown). When the pinions are rotated, the racks are driventransversely to the machine direction to withdraw the drop plates 130and 131 from beneath the panel 1A and cover sheet 20, thereby droppingthe assembly onto the stack 111. As shown in FIG. 10 the drop plateshave a unique edge configuration which particularly enhances theintegrity of the finished panel product.

It will be appreciated that as the drop plates 130 and 131 arewithdrawn, the panel tends to sag in its middle. The sagging or flexingof the panel, particularly in the thicker panels, can cause the layersof the panel to move transversely with respect to each other and thus toseparate. This causes a loss of integrity and bonding between the layersand can significantly reduce the strength characteristics of thefinished panel. The apparatus and method of the present invention,however, significantly reduces the flexing of the panel in the stackingoperation, as will now be described.

Particularly, the drop plates 130 and 131 have tapered edges as shown at140-143. In drop plates of about seven feet in length in the machinedirection, the taper begins at a point about two feet, in the machinedirection, from the leading edge 112, and extends rearwardly toward edge112, and outwardly about four inches. Also, the taper begins at the samepoint and moves generally in the machine direction and outwardly aboutfour inches at the other end of the plates. The tapering of the edges inthis manner, as opposed to simply having straight panel edges parallelto the machine direction, accomplishes a unique result. That is, as thedrop plates 130 and 131 are withdrawn from beneath the panel 1A, thecentral portions of the panel 1A remain supported while the drop platessupport is first removed from beneath the corners of the panel. Forexample, as the drop plates 130 and 131 are withdrawn to the respectivepositions 130A and 131A, as shown in the phantom lines, it will be notedthat the corners of the panel 1A are free to drop and yet the centralportion of the panel in the area of the line 1B tends to remainsupported by a portion of the drop plates. The dropping first of thecorners of the panel 1A, as opposed to dropping the whole panel byremoving drop plates having straight edges, tends to reduce the saggingof the panel 1A in the middle, until the last moment. While the cornersmay slightly flex, that flexing is not to such a great degree as thesagging of the panel could be in the middle, should the edges of thedrop plates be parallel and thus be withdrawn from beneath the panel atthe same time.

Accordingly, the flexing of the panel is distributed at the lightercorner areas, rather than in the center area, as the drop plates arewithdrawn and this, in combination with the relatively quick motion ofthe drop plates from beneath the panel and the carrier sheet, tends tominimize flexing of the panel, distributing this flex over differentgreater areas than the center alone and thus enhances the integrity ofthe finished product. Finally, the drop plates are removed to thepositions shown at 130B and 131B whereby the complete panel is permittedto drop onto the stack 111. Of course, the motion of the plates iscontinuous and rapid.

Several further considerations should here be noted. For example, inFIG. 10, a maximum length panel is shown engaging the stops 114 so thatthe line 1B is not in the direct center of the panel 1A. When shorterpanels are utilized, however, the tapering of the drop plates 130 and131, as shown, are more centrally localized beneath the shorter panels,this by virtue of the moving of the stops 114 in the opposite directionof the machine direction in order to accommodate the shorter panels. Inany event, the tapering of the drop plates 130 and 131 as abovedescribed serves to significantly reduce panel flex for all size panels,for example, those of 3, 4 or even 6 to 7 feet in length, and in eachcase serve to support the center area of the panel until the lastmoment, thereby reducing flex. Thus, while the panels flex somewhat, thetapering of the drop plates 130 and 131 significantly minimizes thisflex so as to reduce or eliminate layer separation.

The stacking apparatus also includes a stack support for raising and thelowering of the stack, as will now be described. More particularly,minimization of the dropping distance of the panel is important in orderto ensure uniform edges and less panel flex. Accordingly, it is desiredto drop each panel through only as short a distance as possible.Accordingly, the conveyor 125 is mounted on a scissors linkage 150,connected to an appropriate hydraulic cylinder 151. When pressurized,the cylinder 151 serves to extend the linkage and thus to raise theconveyor 125 toward the drop table 113. On the other hand, when thecylinder is vented, it permits the scissors linkage 150 to compress,thereby lowering the conveyor 125 and the stack 111 from the drop table.

In the preferred method, it is desired to drop the panel on the droptable the shortest distance. Thus the cylinder 151 is controlled toraise the stack 111 to just immediately underneath the drop table 113for each panel which is to be dropped. To this end, the stackingapparatus is provided with the photo electric sensing apparatus 155positioned across the stack 111, as shown in FIGS. 3B and 12. The photosensing apparatus is connected to an electrical hydraulic cylindercontrol of any suitable type.

As the pusher dog 97 traverses to its end position 99 (FIG. 3B), a limitswitch LS-1 is engaged and signals a suitable drop plate control toactuate the pinion driving mechanism (not shown) to open the dropplates. This occurs after a predetermined delay to ensure that the panelis in the appropriate position on the drop table, against the stops. Asthe drop plate control operates the drop plate, it also is operable tosignal a cylinder control which causes the cylinder to vent, permittingthe scissors linkage 150 to relax and the stack 111 to thereby lower,also, after a predetermined delay to permit the panel 1A to fall to thetop of the stack before lowering of the stack. As the cylinder 151 isvented, the stack 111 continues to lower and falls beneath the photosensing apparatus 155. A beam is made across the top of the stack and,upon making the beam, the photo sensor signals the cylinder controlwhich pressurizes the cylinder. Pressurization of the cylinder 151extends the scissors linkage 150, thereby raising the stack 111 untilsuch time as the beam of the photo sensing apparatus 155 across thestack 111 is broken. At this point, the photo sensor again signals thecylinder control, which is operable to stop the cylinder in staticcondition and maintain the stack 111 in a raised position. Thepositioning of the photo sensing apparatus 155 is thus important tominimizing the drop distance. It is positioned as high as possible sothat the uppermost panel on the stack 111 is as close as possible to theunderneath surface of the drop plates 130 and 131. In this manner, thestack 111 is raised to the highest possible position so that theuppermost panel on the stack is in the same position relative to thedrop plates as was the immediately underneath panel when the uppermostpanel was dropped. Accordingly, the stacking apparatus is then incondition to receive another panel which is dropped only a shortdistance, preferably just greater than that of the thickness of the dropplates.

Accordingly, the combination of the configuration of the drop plates,together with the functional features of the stacking apparatus wherebythe drop distance is minimized, acts to substantially reduce flexing anddisturbance of the uncured panel throughout the dropping operation.

As the stack 111 grows by virtue of succeedingly dropped panels, thescissors mechanism is eventually lowered to a point where the conveyorapparatus tends to rest on off center stops 160 and 161. While thescissors linkage has been described as a single unit for clarity, asshown in FIG. 11, two scissors linkages 150A and 150B, together withappropriate cylinders, are provided. The scissors linkages operatesimultaneously, until such time as the stops 160 and 161 are engaged. Atthis point, and during venting of the cylinders 151A and 151B, thescissors linkages are relaxed. By virtue of the fact that the stops 160and 161 are off center, as shown in FIG. 11, however, the lefthand endof the conveyor 125, as viewed in FIG. 11, is permitted to drop belowthe righthand end, thus forming an incline, and the stack 111 on itspallet 120 tends to roll down the conveyor 125 onto a takeoff conveyor126 for movement to a further curing and storage area.

While several control functions have been described and illustrated, forexample in FIG. 12, it should be noted that any suitable mechanisms andcontrols as as well known can be utilized to accomplish these newfunctions as described, and the particular mechanisms form on part ofthis invention.

Having now described the invention in detail, further advantages andmodifications which can be made without departing from the scope of theinvention will be appreciated by those of ordinary skill in the art, andthe applicant intends to be bound only by the claims appended hereto.

I claim:
 1. A method for manufacturing cementitious panels of the typehaving a nailable cementitious aggregate core faced on each major sidewith a reinforcing element bathed in a slurry comprising hydrauliccement, the method comprising the steps of:running an elongatedindefinite length web of pervious reinforcing material through a slurrybath and depositing an amount of slurry thereto to form a first wetuncured flexible cementitious element; depositing cementitious aggregatecore material on said uncured flexible cementitious element; running asecond elongated indefinite length web of pervious reinforcing materialthrough a second slurry bath, and depositing an amount of slurry theretoto form a second wet uncured flexible cementitious element; laying thesecond element on said core material; thereby adhering the elements torespective major sides of said aggregate core material to form anuncured panel web; thereafter cutting said uncured panel web to formseparate uncured cementitious panels; and thereafter curing said panels.2. Method as in claim 1 including the step of stacking said uncuredcementitious panels and curing same in stacked form.
 3. Method as inclaim 1 including the step of laying the first uncured element on aplurality of abutted moving carrier sheets.
 4. Method of claim 3including the step of cutting said uncured panel web to form separateuncured cementitious panels by cutting said uncured panel web betweensaid abutting carrier sheets while said uncured panel web lies on saidsheets.
 5. A method as in claim 1 including the step of compacting saidcore material against said first element, prior to laying said secondelement thereon.
 6. A method as in claim 1 including the step ofmetering the amount of slurry applied to said first elongated web.
 7. Amethod as in claim 6 including dragging a surface of said web whereby atleast said first elongated web floats on a portion of said slurrythereon during formation of said cementitious panels to bond said firstelement to said core.
 8. A method as in claim 1 comprising the furtherstep of stacking said separate cementitious panels, atop one another,for curing, said stacking comprising the steps of sequentially conveyingseparate uncured panels onto a drop table; withdrawing the table frombeneath the panel thereon; and dropping the panel onto previouslydropped panels to form a stack of panels.
 9. A method as in claim 8wherein the drop table comprises movable drop plates and including thestep of withdrawing said drop plates first from beneath corners of saidpanels, and then from central portions thereof to minimize panel flex.10. A method as in claim 1 including the step of cutting said uncuredpanel web by drawing a knife across said web and from one edge thereofto another to form said separate uncured cementitious panels while saidweb is moving.
 11. A method for manufacturing cementitious panels of thetype having a nailable cementitious aggregate core faced on each majorside with a reinforcing element bathed in a slurry comprising hydrauliccement, the method comprising the steps of:running an elongatedindefinite length web of pervious reinforcing material through a slurrybath, and metering the amount of slurry adhering thereto to form a firstuncured flexible web of reinforcement material; laying the first uncuredreinforcement material indefinite length web on a plurality of abutted,moving carrier sheets; depositing cementitious aggregate core materialon said web; compacting said core material; running a second elongatedindefinite length web of pervious reinforcing material through a secondslurry bath, and metering the amount of slurry adhering thereto to forma second uncured flexible web of reinforcement material; laying thesecond uncured reinforcing material indefinite length web on saidcompacted core material; thereby adhering the reinforcing webs torespective major sides of said aggregate core material to form anuncured panel web; thereafter cutting said uncured panel web to formseparate cementitious panels, by drawing a knife across said uncuredpanel web from one edge thereof to another and between said carriersheets while said uncured panel web lies on said sheets; and thereaftercuring said panels.
 12. A method as in claim 11 including the steps ofdragging the respective upper surfaces of each reinforcing web,subsequent to said metered application of said slurry thereto, wherebysaid slurry is driven through said pervious reinforcing webs, andresides on both faces thereof, said slurry operably adhering saidreinforcing webs to said aggregate core material.
 13. A method as inclaim 11 comprising the further step of stacking said separatecementitious panels, atop one another, for curing.
 14. A method as inclaim 13 wherein said stacking comprises conveying said separate carriersheet supported panels onto a drop table comprising transversely movabledrop plates; sliding said drop panels from beneath said carrier sheet;and dropping said carrier sheet and panel thereon onto a preceding panelto form a stack of panels.
 15. A method as in claim 14 wherein said dropplates are tapered, and including the step of withdrawing said platesfirst from beneath corners of said panels and carrier sheets, and thenfrom central portions thereof to minimize panel flex.
 16. A method as inclaim 14 including sequentially lowering said stack of panels to receivea further carrier sheet and panel.
 17. A method as in claim 11 includingthe steps of pushing cut panels on their associated carrier sheets ontopanel drop plates, withdrawing said plates in response to the completionof said pushing to drop a carrier sheet and panel thereon onto a stackof panels, lowering said stack of panels in response to operation ofsaid drop plates after a carrier sheet and panel have dropped thereon;and thereafter raising said stack of panels to a position for receivinganother carrier sheet and panel from said drop plates.
 18. A method asin claim 17 including the step of sensing the lowering of said stack andthereafter raising the stack such that the last dropped panel is in thesame position relative to the drop plates as was the panel immediatelybeneath the last dropped panel at the time it was dropped.
 19. A methodas in claim 11 wherein said cutting includes the step of sensing saidcarrier sheets and cutting said panels between said carrier sheets inresponse to said sensing.
 20. A method as in claims 11 or 19 includingthe step of stopping said carrier sheets and cutting said webtherebetween.
 21. A method as in claims 11 or 19 including the step ofcutting said panel web between said carrier sheets when said carriersheets are moving.
 22. A method as in claims 11 or 19 includingconveying separate panels away from said panel web, after said cutting,on an overspread conveyor at a speed in excess of that of said panelweb.
 23. A method for manufacturing cementitious panels of the typehaving a nailable cementitious aggregate core faced on each major sidewith a reinforcement element bathed in a slurry comprising hydrauliccement, the method comprising the steps of:forming an elongated uncuredpanel web, comprising said core and said reinforcing elements, on movingabutting carrier sheets; thereafter cutting said uncured web to formseparate cementitious panels, one on each carrier sheet, by cutting saidweb transversely between said sheets; and thereafter curing said panels.24. A method as in claim 23 comprising the step of sensing a carriersheet and cutting across said web from one edge thereof to anotherbetween said sensed carrier sheet and an adjacent carrier sheet, inresponse to said sensing.
 25. A method as in claim 24 including stoppingsaid web in response to said sensing and then cutting it.
 26. A methodas in claim 24 including the step of sensing a moving carrier sheet, andcutting said web between said sensed sheet and an adjacent sheet whilesaid sheets are moving.
 27. A method as in claim 25 including cuttingsaid panel web transversely in one direction between said sensed carriersheet and said adjacent carrier sheet and then in a second oppositetransverse direction in response to sensing an immediately followingcarrier sheet.
 28. A method as in claim 4 wherein said uncured panel weblies in a substantially horizontal plane and wherein said step ofcutting includes drawing a knife cutting edge through and across saiduncured panel web, said knife cutting edge being disposed substantiallyperpendicular to said uncured panel web and said plane.
 29. A method asin claim 11 wherein said uncured panel web lies in a substantiallyhorizontal plane and wherein said step of cutting includes drawing aknife cutting edge through and across said uncured panel web, said knifecutting edge being disposed substantially perpendicular to said uncuredpanel web and said plane.
 30. A method as in claim 23 wherein saiduncured panel web lies in a substantially horizontal plane and whereinsaid step of cutting includes drawing a knife cutting edge through andacross said uncured panel web, said knife cutting edge being disposedsubstantially perpendicular to said uncured panel web and said plane.31. A method for manufacturing cementitious panels of the type having anailable cementitious core faced on each major side with a reinforcingelement bathed in a slurry comprising hydraulic cement, the methodcomprising the steps of:running a first elongated indefinite length webof reinforcing material through a slurry bath and depositing said slurrythereto to form a first uncured flexible cementitious element; meteringthe amount of slurry deposited on said first web; dragging an uppersurface of said web against a bar to force slurry into said web, whileleaving slurry on said upper surface; depositing cementitious aggregatecore material on said uncured flexible cementitious element; running asecond elongated indefinite length web of reinforcing material through asecond slurry bath, and depositing slurry thereto to form a seconduncured flexible cementitious element; metering the amount of slurrydeposited on said first web; dragging an upper surface of said webagainst a bar to force slurry into said web, while leaving slurry onsaid upper surface; laying the second element on said core material;thereby adhering the elements to respective major sides of saidaggregate core material to form an uncured panel web; and thereaftercuring said panel.
 32. A method for manufacturing cementitious panels ofthe type having a nailable cementitious no slump aggregate core faced oneach major side with a reinforcing element bathed in a slurry comprisinghydraulic cement, the method comprising the steps of:running anelongated indefinite web of pervious reinforcing mesh material through aslurry bath and depositing an amount of slurry thereto to form a firstwet uncured flexible cementitious element; depositing cementitious noslump aggregate core material on said uncured flexible cementitiouselement; running a second elongated indefinite length web of perviousreinforcing mesh material through a second slurry bath, and depositingan amount of slurry thereto to form a second wet, uncured flexiblecementitious element; said slurry residing on both sides of said firstand second webs and within interstices of said mesh material; laying thesecond element on said core material; adhering by the bonding of saidslurry the elements to respective major sides of said aggregate corematerial to form an uncured panel web; thereafter cutting said uncuredpanel web to form separate uncured cementitious panels; and thereaftercuring said panels.